Siegel recently distinguishes between seven possible ways in which our perceptual access to social information can be biased by flawed practice of either individuals or social structures, two of which, namely attention and cognitive penetration, imply that it is the content of perception, as opposed to that of judgments, that is biased. Both attention and cognitive penetration, however, rely on cognitive states imposing top-down influences on perceptual states. As such, perceptual bias resulting from them is to a large extent merely (...) a derivation of cognitive bias. In this paper, I propose another way in which our perception can be biased, namely, as the result of faulty assumptions made by the visual system. Furthermore, I argue that in contrast to cognitive penetration and attentional direction, perceptual bias arising in this way is fundamentally perceptual and does not depend on inputs from one’s cognitive system. This sort of perceptual bias, if it exists, would have important implications for how we conceptualize social bias and pose special challenges to traditional interventions designed to counteract bias. (shrink)

Vision is known to improve human postural responses to external perturbations. This study investigates the role of vision for the responses to continuous pseudorandom support surface translations in the body sagittal plane in three visual conditions: with the eyes closed, in stroboscopic illumination and with eyes open in continuous illumination with the room as static visual scene. In the frequency spectrum of the translation stimulus we distinguished on the basis of the response patterns between a low-frequency, mid-frequency, and (...) high-frequency range. With EC, subjects’ mean sway response gain was very low in the LFR. On average it increased with EO/SI and more so with EO/CI. In contrast, the average gain in the MFR decreased from EC to EO/SI and further to EO/CI. In the HFR, all three visual conditions produced, similarly, high gain levels. A single inverted pendulum model controlling center of mass balancing about the ankle joints formally described the EC response as being strongly shaped by a resonance phenomenon arising primarily from the control’s proprioceptive feedback loop. The effect of adding visual information in these simulations lies in a reduction of the resonance, similar as in the experiments. Extending the model to a double inverted pendulum suggested in addition a biomechanical damping effective from trunk sway in the hip joints on the resonance. (shrink)

The burgeoning interest in arts-informed research and the increasing variety of visual possibilities as a result of new technologies have paved the way for researchers to explore and use visual forms of inquiry. This article investigates how collage making and concept mapping are useful visual approaches that can inform qualitative research. They are experiential ways of doing/knowing that help to get at tacit aspects of both understanding and process and to make these more explicit to the researcher (...) and more accessible to audiences. It outlines specific ways that each approach can be used with examples to illustrate how the approach informs the researcher's experience and that of the audience. The two approaches are compared and contrasted and issues that can arise in the work are discussed. (shrink)

Milner and Goodale have advanced a justly influential theory of the structure of the human visual system. In broad outline, Milner and Goodale hold that the ventral neural pathway is associated with recognition and experiential awareness, and with a kind of indirect control of action. And they hold that, by contrast, the dorsal neural stream is associated with the non-conscious, direct control of visually informed action. Most of the relevant empirical research has focused on the visual control of (...) close-in, “personal space,” reaching and/or grasping. While their view has not escaped controversy and debate, we think that Milner and Goodale have a compelling story to tell about the visual guidance of such close in, “personal space” action. However, the question of whether their scheme applies to behavior with visually specified targets that are outside of the space accessible by simply reaching and grasping is largely unstudied. And it should be studied, since this is the arena of much human behavior. We provide good reason to think that the Milner and Goodale scheme may well not apply to important classes of mid-range, ‘action space’ behavior. But the matter is in the end to be decided in the lab. We describe a research program to do this. (shrink)

Two visual world experiments investigated the processing of the implicature associated with some using a “gumball paradigm.” On each trial, participants saw an image of a gumball machine with an upper chamber with orange and blue gumballs and an empty lower chamber. Gumballs dropped to the lower chamber, creating a contrast between a partitioned set of gumballs of one color and an unpartitioned set of the other. Participants then evaluated spoken statements, such as “You got some of the blue (...) gumballs.” Experiment 1 investigated the time course of the pragmatic enrichment from some to not all when the only utterance alternatives available to refer to the different sets were some and all. In Experiment 2, the number terms two, three, four, and five were also included in the set of alternatives. Scalar implicatures were delayed relative to the interpretation of literal statements with all only when number terms were available. The results are interpreted as evidence for a constraint-based account of scalar implicature processing. (shrink)

Irvin Rock's hypothesis that certain stages of perceptual processing resemble problem solving in cognition is contrasted to some recent work in computer vision (Marr, Ullman) which tries to reduce intelligence in perception to computational organization. The focal example is subjective contours which Marr thought could be handled by computational modules without descending control, and which Rock thinks are the outcome of intelligent processing.

Bayes’ formula is a fundamental statistical method for inference judgments in uncertain situations used by both laymen and professionals. However, since people often fail in situations where Bayes’ formula can be applied, how to improve their performance in Bayesian situations is a crucial question. We based our research on a widely accepted beneficial strategy in Bayesian situations, representing the statistical information in the form of natural frequencies. In addition to this numerical format, we used five visualizations: a 2×2-table, a unit (...) square, an icon array, a tree diagram, and a double-tree diagram. In an experiment with 688 undergraduate students, we empirically investigated the effectiveness of three graphical properties of visualizations: area-proportionality, use of discrete and countable statistical entities, and graphical transparency of the nested-sets structure. We found no additional beneficial effect of area-proportionality. In contrast, the representation of discrete objects seems to be beneficial. Furthermore, our results show a strong facilitating effect of making the nested-sets structure of a Bayesian situation graphically transparent. Our results contribute to answering the questions of how and why a visualization could facilitate judgment and decision making in situations of uncertainty. (shrink)

The purpose of this paper is to defend what I call the action-oriented coding theory (ACT) of spatially contentful visual experience. Integral to ACT is the view that conscious visual experience and visually guided action make use of a common subject-relative or 'egocentric' frame of reference. Proponents of the influential two visual systems hypothesis (TVSH), however, have maintained on empirical grounds that this view is false (Milner & Goodale, 1995/2006; Clark, 1999; 2001; Campbell, 2002; Jacob & Jeannerod, (...) 2003; Goodale & Milner, 2004). One main source of evidence for TVSH comes from behavioral studies of the comparative effects of size-contrast illusions on visual awareness and visuo- motor action. This paper shows that not only is the evidence from illusion studies inconclusive, there is a better, ACT-friendly interpretation of the evidence that avoids serious theoretical difficulties faced by TVSH. (shrink)

This paper concerns local yet systematic problems of contrastive underdetermination of model choice in cognitive neuroscience debates about the so-called two visual systems hypothesis. The underdetermination problem is systematically generated by the way certain assumptions about the representationalist nature of computation are translated into experimental practice. The problem is that behavioural data underdetermine the choice between competing representational models. In this paper, I diagnose how these assumptions generate underdetermination problems in the choice between competing functional models of perception–action. Using (...) the tools of philosophy of science, I describe the type of underdetermination and sketch a possible cure. (shrink)

Image similarity metric, also known as metric learning in computer vision, is a significant step in various advanced image tasks. Nevertheless, existing well-performing approaches for image similarity measurement only focus on the image itself without utilizing the information of other modalities, while pictures always appear with the described text. Furthermore, those methods need human supervision, yet most images are unlabeled in the real world. Considering the above problems comprehensively, we present a novel visual similarity metric model named PTF-SimCM. It (...) adopts a self-supervised contrastive structure like SimSiam and incorporates a multimodal fusion module to utilize textual modality correlated to the image. We apply a cross-modal model for text modality rather than a standard unimodal text encoder to improve late fusion productivity. In addition, the proposed model employs Sentence PIE-Net to solve the issue caused by polysemous sentences. For simplicity and efficiency, our model learns a specific embedding space where distances directly correspond to the similarity. Experimental results on MSCOCO, Flickr 30k, and Pascal Sentence datasets show that our model overall outperforms all the compared methods in this work, which illustrates that the model can effectively address the issues faced and enhance the performances on unsupervised visual similarity measuring relatively. (shrink)

PurposeTo evaluate the relationship between intraocular straylight perception and: (i) contrast sensitivity (CS), (ii) halo size, and (iii) hazard recognition distance, in the presence and absence of glare.Subjects and methodsParticipants were 15 (5 female) ophthalmologically healthy adults, aged 54.6–80.6 (median: 67.2) years. Intraocular straylight (log s) was measured using a straylight meter (C-Quant; Oculus GmbH, Wetzlar, Germany). CS with glare was measured clinically using the Optovist I device (Vistec Inc., Olching, Germany) and also within a driving simulator using Landolt Cs. (...) These were presented under both static or dynamic viewing conditions, and either with or without glare. Hazard detection distance was measured for simulated obstacles of varying contrast. For this, the participant was required to maintain a speed of 60 km/h within a custom-built nighttime driving simulator. Glare was simulated by LED arrays, moved by cable robots to mimic an oncoming car’s headlights. Halo size (“halometry”) was measured by moving Landolt Cs outward originating from the center of a static glare source. The outcome measure from “halometry” was the radius of the halo (angular extent, in degrees visual angle).ResultsThe correlation between intraocular straylight perception, log s, and hazard recognition distance under glare was poor for the low contrast obstacles (leading/subdominant eye: r = 0.27/r = 0.34). Conversely, log CS measured with glare strongly predicted hazard recognition distances under glare. This was true both when log CS was measured using a clinical device (Optovist I: r = 0.93) and within the driving simulator, under static (r = 0.69) and dynamic (r = 0.61) conditions, and also with “halometry” (r = 0.70). Glare reduced log CS and hazard recognition distance for almost all visual function parameters.ConclusionIntraocular straylight was a poor predictor of visual function and driving performance within this experiment. Conversely, CS was a strong predictor of both hazard recognition and halo extent. The presence of glare and motion lead to a degradation of CS in a driving simulator. Future studies are necessary to evaluate the effectiveness of all above-mentioned vision-related parameters for predicting fitness to drive under real-life conditions. (shrink)

The two contrasting theoretical approaches to visual perception, the constructivist and the ecological, are briefly presented and illustrated through their analyses of space and size perception. Earlier calls for their reconciliation and unification are reviewed. Neurophysiological, neuropsychological, and psychophysical evidence for the existence of two quite distinct visual systems, the ventral and the dorsal, is presented. These two perceptual systems differ in their functions; the ventral system's central function is that of identification, while the dorsal system is mainly (...) engaged in the visual control of motor behavior. The strong parallels between the ecological approach and the functioning of the dorsal system, and between the constructivist approach and the functioning of the ventral system are noted. It is also shown that the experimental paradigms used by the proponents of these two approaches match the functions of the respective visual systems. A dual-process approach to visual perception emerges from this analysis, with the ecological-dorsal process transpiring mainly without conscious awareness, while the constructivist-ventral process is normally conscious. Some implications of this dual-process approach to visual-perceptual phenomena are presented, with emphasis on space perception. Key Words: constructivist; dual-process approach; ecological; size perception; space perception; two visual systems; visual perception theories. (shrink)

A set of visual search experiments tested the proposal that focused attention is needed to detect change. Displays were arrays of rectangles, with the target being the item that continually changed its orientation or contrast polarity. Five aspects of performance were examined: linearity of response, processing time, capacity, selectivity, and memory trace. Detection of change was found to be a self-terminating process requiring a time that increased linearly with the number of items in the display. Capacity for orientation was (...) found to be about 5 items, a value comparable to estimates of attentional capacity. Observers were able to filter out both static and dynamic variations in irrelevant properties. Analysis also indicated a memory for previously-attended locations. These results support the hypothesis that the process needed to detect change is much the same as the attentional process needed to detect complex static patterns. Interestingly, the features of orientation and polarity were found to be handled in somewhat different ways. Taken together, these results not only provide evidence that focused attention is needed to see change, but also show that change detection itself can provide new insights into the nature of attentional processing. (shrink)

In this paper, I take up the conciliatory-steadfast debate occurring within social epistemology in regards to the phenomenon of peer disagreement. I will argue, because the conciliatory perspective al-lows us to understand argumentation pragmatically—as a method of problem-solving within a community rather than as a method for obtaining the truth—that in most cases, we should not simply agree to disagree.

Visual aids can improve comprehension of risks associated with medical treatments, screenings, and lifestyles. Do visual aids also help decision makers accurately assess their risk comprehension? That is, do visual aids help them become well calibrated? To address these questions, we investigated the benefits of visual aids displaying numerical information and measured accuracy of self-assessment of diagnostic inferences (i.e., metacognitive judgment calibration) controlling for individual differences in numeracy. Participants included 108 patients who made diagnostic inferences about (...) three medical tests on the basis of information about the sensitivity and false-positive rate of the tests and disease prevalence. Half of the patients received the information in numbers without a visual aid, while the other half received numbers along with a grid representing the numerical information. In the numerical condition, many patients --especially those with low numeracy-- misinterpreted the predictive value of the tests and profoundly overestimated the accuracy of their inferences. Metacognitive judgment calibration mediated the relationship between numeracy and accuracy of diagnostic inferences. In contrast, in the visual aid condition, patients at all levels of numeracy showed high-levels of inferential accuracy and metacognitive judgment calibration. Results indicate that accurate metacognitive assessment may explain the beneficial effects of visual aids and numeracy --a result that accords with theory suggesting that metacognition is an essential part of risk literacy. We conclude that well-designed risk communications can inform patients about health-relevant numerical information while helping them assess the quality of their own risk comprehension. (shrink)

In this paper I argue that causal relations between objects are represented in visual experience, and contrast my argument and its conclusion with Michotte's results from the 1960's.

Susanna Siegel argues that visual contents are rich: visual experiences represent a variety of properties, over and above mere colors and shapes, including, notably, kind properties, e.g., the property of being a pine tree. To argue her case, she makes use of the method of phenomenal contrasts, which involves choosing among different explanatory hypotheses to account for phenomenal contrasts between relevant experiences. I will argue that there is reason to question whether the method of phenomenal contrasts is suitable (...) for establishing that kind properties are represented in visual experiences, insofar as the method draws upon first-person intuitions eclectically. (shrink)

Molyneux’s question famously asks about whether a newly sighted subject might immediately recognize, by sight alone, shapes that were already familiar to her from a tactile point of view. This paper addresses three crucial points concerning this puzzle. First, the presence of two different questions: the classic one concerning visual recognition and another one concerning vision-for-action. Second, the explicit distinction, reported in the literature, between ocular and cortical blindness. Third, the importance of making reference to our best neuroscientific account (...) on vision, ‘the two visual systems model’, in order to better address Molyneux’s problem. Then, by offering a new, deeper analysis of the relation between, and, this paper suggests that the subjects of Molyneux’s two different questions show the same visual impairment as brain-damaged subjects with different lesions of the visual cortex. In particular, the subject of the first question shows the same impairment in visual recognition as a visual agnosic subject, while the subject of the second question shows the same visual impairment in visuomotor processing as an optic ataxic subject. These impairments still hold even if ocular processing is restored. Therefore, I suggest the following. For the first classic question, the required experimental setting cannot be properly reached. By contrast, concerning the second question, based on the interpretation we select, either the answer is negative, or, as with the first question, the experimental setting cannot be properly reached. This proposal constitutes, with the other approaches offered in the literature, a further attempt to tackle the enormous complexity of Molyneux’s puzzle. (shrink)

Evidence from adult studies of deaf signers supports the dissociation between neural systems involved in processing visual linguistic and non-linguistic body actions. The question of how and when this specialization arises is poorly understood. Visual attention to these forms is likely to change with age and be affected by prior language experience. The present study used eye-tracking methodology with infants and children as they freely viewed alternating video sequences of lexical American sign language (ASL) signs and non-linguistic body (...) actions (self-directed grooming action and object-directed pantomime). In Experiment 1, we quantified fixation patterns using an area of interest (AOI) approach and calculated face preference index (FPI) values to assess the developmental differences between 6 and 11-month-old hearing infants. Both groups were from monolingual English-speaking homes with no prior exposure to sign language. Six-month-olds attended the signer’s face for grooming; but for mimes and signs, they were drawn to attend to the “articulatory space” where the hands and arms primarily fall. Eleven-month-olds, on the other hand, showed a similar attention to the face for all body action types. We interpret this to reflect an early visual language sensitivity that diminishes with age, just before the child’s first birthday. In Experiment 2, we contrasted 18 hearing monolingual English-speaking children (mean age of 4.8 years) vs. 13 hearing children of deaf adults (CODAs; mean age of 5.7 years) whose primary language at home was ASL. Native signing children had a significantly greater face attentional bias than non-signing children for ASL signs, but not for grooming and mimes. The differences in the visual attention patterns that are contingent on age (in infants) and language experience (in children) may be related to both linguistic specialization over time and the emerging awareness of communicative gestural acts. (shrink)

We investigated how two cues to contrast—beat gesture and contrastive pitch accenting—affect comprehenders' cognitive load during processing of spoken referring expressions. In two visual‐world experiments, we orthogonally manipulated the presence of these cues and their felicity, or fit, with the local (sentence‐level) referential context in critical referring expressions while comprehenders' task‐evoked pupillary responses (TEPRs) were examined. In Experiment 1, beat gesture and contrastive accenting always matched the referential context of filler referring expressions and were therefore relatively felicitous on the (...) global (experiment) level, whereas in Experiment 2, beat gesture and contrastive accenting never fit the referential context of filler referring expressions and were therefore infelicitous on the global level. The results revealed that both beat gesture and contrastive accenting increased comprehenders' cognitive load. For beat gesture, this increase in cognitive load was driven by both local and global infelicity. For contrastive accenting, this increase in cognitive load was unaffected when cues were globally felicitous but exacerbated when cues were globally infelicitous. Together, these results suggest that comprehenders' cognitive resources are taxed by processing infelicitous use of beat gesture and contrastive accenting to convey contrast on both the local and global levels. (shrink)

Semantic networks were developed in cognitive science and artificial intelligence studies as graphical knowledge representation and inference tools emulating human thought processes. Formal analysis of the representation and inference capabilities of the networks modeled them as subsets of standard first-order logic (FOL), restricted in the operations allowed in order to ensure the tractability that seemed to characterize human reasoning capabilities. The graphical network representations were modeled as providing a visual language for the logic. Sub-sets of FOL targeted on knowledge (...) representation came to be called description logics, and research on these logics has focused on issues of tractability of subsets with differing representation capabilities, and on the implementation of practical inference systems achieving the best possible performance. Semantic network research has kept pace with these developments, providing visual languages for knowledge entry, editing, and presenting the results of inference, that translate unambiguously to the underlying description logics. This paper discusses the design issues for such semantic network formalisms, and illustrates them through detailed examples of significant generic knowledge structures analyzed in the literature, including determinables, contrast sets, genus/differentiae, taxonomies, faceted taxonomies, cluster concepts, family resemblances, graded concepts, frames, definitions, rules, rules with exceptions, essence and state assertions, opposites and contraries, relevance, and so on. Such examples provide important test material for any visual language formalism for logic. (shrink)

The 11 experimental, pseudo-avantgarde visual poems (wordless, other than title and date) are an indirect homage to the late-great filmmaker and photographer, Chris Marker (1921-2012), foremost to his penchant for utilizing disintegrating imagery in his film-essays and multimedia installations. All images were captured using a Research in Motion, BlackBerry 8520 cellphone, and subsequently 100-percent de-saturated, and 100-percent contrast-adjusted, using Microsoft Office Picture Manager. The images, as a result, resemble the primitive production values given to the pinhole camera, and the (...) “dogmatic” (uniform) adjustments (as above), applied to the original BB images, reference the early strictures applied to filmmaking by Lars von Trier. The above-mentioned, black-and-white adjustments notwithstanding, all images are used “as captured,” without cropping. The series begins and ends in Botwnnog, Northwest Wales, in May and August of 2013, respectively, with interregnums and brief idylls in Rijeka, Croatia, Trieste and Ancona, Italy, and Igoumenitsa, Ioannina, and Athens, Greece. Tracking the peregrinations of the author of the poems across Europe, and intimately associated with the then-nascent research and exhibition project, “Not-I/Thou: The Other Subject of Art & Architecture,”* the poems are also a compressed form of scholarship, albeit operating in the shadow-lands of knowledge per se, and evoking the non-discursive side of literary-artistic production, a penumbral zone within cultural production that nonetheless references the discursive arts (essay and/or full-blown treatise), but favors the paradox and/or tautology – privileging, then, the much-desired destruction of dialectics. (shrink)

What do we see? We are visually conscious of colors and shapes, but are we also visually conscious of complex properties such as being John Malkovich? In this book, Susanna Siegel develops a framework for understanding the contents of visual experience, and argues that these contents involve all sorts of complex properties. Siegel starts by analyzing the notion of the contents of experience, and by arguing that theorists of all stripes should accept that experiences have contents. She then introduces (...) a method for discovering the contents of experience: the method of phenomenal contrast. This method relies only minimally on introspection, and allows rigorous support for claims about experience. She then applies the method to make the case that we are conscious of many kinds of properties, of all sorts of causal properties, and of many other complex properties. She goes on to use the method to help analyze difficult questions about our consciousness of objects and their role in the contents of experience, and to reconceptualize the distinction between perception and sensation. Siegel's results are important for many areas of philosophy, including the philosophy of mind, epistemology, and the philosophy of science. They are also important for the psychology and cognitive neuroscience of vision. (shrink)

In psychophysical experiments, the use of a psychophysical procedure of brightness/darkness cancellation shed light on interactions between spatial arrangement and figure–ground contrast in the perceptual filling in of achromatic and colored surfaces.Achromatic and chromatic Kanizsa squares with varying contrast, contrast polarity, and inducer spacingwere used to test how these factors interact in the perceptual filling in of surface brightness or darkness. The results suggest that the neuronal processing of surfaces with apparent contrast, leading to figure–ground segregation (i.e., perceptual organization), is (...) governed by mechanisms that integrate both luminance contrast and spatial information carried by the inducing stimuli, while discarding information on contrast polarity or color. The findings are discussed in relation to earlier observations on brightness assimilation and contrast. They support theories of nonantagonistic neural mechanisms suppressing local contrast or color signs in brightnessbased figure–ground percepts. Such mechanismsmight be necessary to cancel potentially conflicting polarities in geometricallycomplex visual stimuli so that perceptual filling in resulting in the most plausible representation of figure and ground can be achieved. (shrink)

People can discriminate the synchrony between audio-visual scenes. However, the sensitivity of audio-visual synchrony perception can be affected by many factors. Using a simultaneity judgment task, the present study investigated whether the synchrony perception of complex audio-visual stimuli was affected by audio-visual causality and stimulus reliability. In Experiment 1, the results showed that audio-visual causality could increase one's sensitivity to audio-visual onset asynchrony (AVOA) of both action stimuli and speech stimuli. Moreover, participants were more (...) tolerant of AVOA of speech stimuli than that of action stimuli in the high causality condition, whereas no significant difference between these two kinds of stimuli was found in the low causality condition. In Experiment 2, the speech stimuli were manipulated with either high or low stimulus reliability. The results revealed a significant interaction between audio-visual causality and stimulus reliability. Under the low causality condition, the percentage of “synchronous” responses of audio-visual intact stimuli was significantly higher than that of visual_intact/auditory_blurred stimuli and audio-visual blurred stimuli. In contrast, no significant difference among all levels of stimulus reliability was observed under the high causality condition. Our study supported the synergistic effect of top-down processing and bottom-up processing in audio-visual synchrony perception. (shrink)

The visual brain consists of several parallel, functionally specialized processing systems, each having several stages (nodes) which terminate their tasks at different times; consequently, simultaneously presented attributes are perceived at the same time if processed at the same node and at different times if processed by different nodes. Clinical evidence shows that these processing systems can act fairly autonomously. Damage restricted to one system compromises specifically the perception of the attribute that that system is specialized for; damage to a (...) given node of a processing system that leaves earlier nodes intact results in a degraded perceptual capacity for the relevant attribute, which is directly related to the physiological capacities of the cells left intact by the damage. By contrast, a system that is spared when all others are damaged can function more or less normally. Moreover, internally created visual percepts-illusions, afterimages, imagery, and hallucinations-activate specifically the nodes specialized for the attribute perceived. Finally, anatomical evidence shows that there is no final integrator station in the brain, one which receives input from all visual areas; instead, each node has multiple outputs and no node is recipient only. Taken together, the above evidence leads us to propose that each node of a processing-perceptual system creates its own microconsciousness. We propose that, if any binding occurs to give us our integrated image of the visual world, it must be a binding between microconsciousnesses generated at different nodes. Since any two microconsciousnesses generated at any two nodes can be bound together, perceptual integration is not hierarchical, but parallel and postconscious. By contrast, the neural machinery conferring properties on those cells whose activity has a conscious correlate is hierarchical, and we refer to it as generative binding, to distinguish it from the binding that might occur between the microconsciousnesses. (shrink)

Judgments of visual resemblance (‘A looks like B’), unlike other judgments of resemblance, are often induced directly by visual experience. What is the nature of this experience? We argue that the visual experience that prompts a subject looking at A to judge that A looks like B is a visual experience of B. After elucidating this thesis, we defend it, using the ‘phenomenal contrast’ method. Comparing our account to competing accounts, we show that the phenomenal contrast (...) between a visual experience that induces the judgment that A looks like B, and a visual experience that does not induce this judgment, is best explained by the fact that the former visually represents B, whereas the latter does not. (shrink)

This paper is part of an ongoing project devoted to the investigation of the psychotropic brew Ayahuasca from a cognitive-psychological perspective. This perspective contrasts with those of practically all investigations of Ayahuasca which pertain either to the natural sciences-notably botany, pharmacology, brain science and clinical medicine-or to anthropology. Here, I discuss the visualizations induced by Ayahuasca from a structural, as opposed to contentual, point of view. A typology of the structural forms in which visualizations may appear is drawn. Also examined (...) are the various types of interaction a person can have with his/her visions and aspects pertaining to the semantics of visions and their narrative structure. The distinctions drawn are readily applicable to hallucinatory and visionary experiences induced by other agents and in other contexts. Thus, the present typology may be regarded as presenting the foundations for the cognitive-psychological study of such experiences at large. (shrink)

Adaptation can optimize information processing by allowing the visual system to always adjust to the environment. However, only a few studies have investigated how the visual system makes adjustments to repeatedly occurring changes in the input, still less about the related neural mechanism. Our previous study found that contrast adaptation attenuated after multiple daily sessions of repeated adaptation, which was explained by the habituation of either the adapter’s effective strength or the adaptation mechanisms. To examine the former hypothesis, (...) in the present study we used the frequency tagging technique to measure the adapter-elicited steady-state visual evoked potential amplitudes. Participants repeatedly adapted to the same contrast adapter in a top-up manner for six continuous days, which was called training of adaptation. The behavioral adaptation effect and SSVEP response to the trained adapter and an untrained control adapter were measured before and after training. The psychophysical results showed that the effect of adaptation in the trained condition significantly reduced after training, replicating our previous finding. Contradicting the prediction of the hypothesis that repeated adaptation attenuated the effective strength of the adapter, the SSVEP amplitude was unchanged after training, which was further confirmed by an equivalence test. Taken together, the results challenge the account of habituation of adapter in repeated adaptation, while leaving the account of habituation of adaptation mechanism to be tested. (shrink)

Diagrams are hybrid entities, which incorporate both linguistic and pictorial elements, and are crucial to any account of scientific and mathematical reasoning. Hence, they offer a rich source of examples to examine the relation between model-theoretic considerations and linguistic features. Diagrams also play different roles in different fields. In scientific practice, their role tends not to be evidential in nature, and includes: highlighting relevant relations in a micrograph ; sketching the plan for an experiment; and expressing expected visually salient information (...) about the outcome of an experiment. None of these traits are evidential; rather they are all pragmatic. In contrast, in mathematical practice, diagrams are used as heuristic tools in proof construction ; notational devices; and full-blown proof procedures. Some of these traits are evidential. After assessing these different roles, I explain why diagrams are used in the way they are in these two fields. The result leads to an account of different styles of scientific reasoning within a broadly model-based conception. (shrink)